Protein Kinases are receptor type or non-receptor type proteins, which transfer the terminal phosphate of ATP to aminoacid residues, such as tyrosine, threonine, serine residues, of proteins, thereby activating or inactivating signal transduction pathways. These proteins are known to be involved in many cellular mechanisms, which in case of disruption, lead to disorders such as abnormal cell proliferation and migration as well as inflammation.
As of today, there are over 500 known Protein kinases. Included are the well-known Ab1, Akt1, Akt2, Akt3, ALK, Alk5, A-Raf, Ax1, B-Raf, Brk, Btk, Cdk2, Cdk4, Cdk5, Cdk6, CHK1, c-Raf-1, Csk, EGFR, EphA1, EphA2, EphB2, EphB4, Erk2, Fak, Fes, Fer, FGFR1, FGFR2, FGFR3, FGFR4, Flt-3, Fms, Frk, Fyn, Gsk3α, Gsk3β, HCK, Her2/Erbb2, Her4/Erbb4, IGF1R, IKK beta, Irak4, Itk, Jak1, Jak2, Jak3, Jnk1, Jnk2, Jnk3, KDR, Kit, Lck, Lyn, MAP2K1, MAP2K2, MAP4K4, MAPKAPK2, Met, Mer, MNK1, MLK1, mTOR, p38, PDGFRα, PDGFR β, PDPK1, PI3Kα, PI3Kβ, PI3Kδ, PI3Kγ, Pim1, Pim2, Pim3, PKC alpha, PKC beta, PKC theta, Plk1, Pyk2, Ret, ROCK1, ROCK2, RON, Src, Stk6, Syk, TEC, Tie2, TrkA, TrkB, Tyk2, VEGFR1/Flt-1, VEGFR2/Kdr, VEGFR3/Flt-4, Yes, and Zap70.
Spleen tyrosine kinase (Syk), an intracellular protein tyrosine kinase, is a key mediator of immunoreceptor signalling in a host of inflammatory cells including B cells, mast cells, macrophages, and neutrophils (Wong Br et al (2004), Expert Opin. Investig. Drugs, 13, 743-762). Syk is also widely expressed in nonhematopoietic cells like fibroblasts, breast cancer cells, colonic carcinoma cells, hepatocytes, neuronal cells, and vascular endothelial cells (Okamura S et al (1999), Oncol. Res. 11, 281-285). Originally, Syk was thought to function primarily in signaling of immunoreceptors such as Fc receptor (FcR) and B cell receptor (BCR). However, recent studies demonstrated the crucial role of Syk in the cell signaling of diverse cellular stimuli including IL-1, tumor necrosis factor-ca (TNFα), lipopolysaccharide, and p31-integrin (Yamada T et al (2001), J. Immunol., 167, 283-288). For instance, Syk can be activated by TNFα, resulting in MAPK phosphorylation and NF-κB translocation in hematopoietic cell lines (Takada Y and Aggarwal BB (2004), J. Immunol., 173, 1066-1077). IL-1-induced chemokine production in fibroblasts of nasal polyps is also mediated by Syk activation (Yamada T et al (2001), J. Immunol., 167, 283-288). Syk has emerged as a potential therapeutic target for treatment of allergic and autoimmune disorders.
Existing compounds active on protein kinases are not always endowed with satisfactory properties such as potency, selectivity, stability and solubility. Additionally, existing compounds active on protein kinases are not always endowed with satisfactory in vivo bioavailability.
The present invention discloses compounds that display potent and selective inhibitory activity on wild type and/or mutated protein kinase, in particular wild type and/or mutated tyrosine kinase, and more particularly Syk. In particular, the present invention discloses compounds for selectively modulating, regulating, and/or inhibiting signal transduction mediated by certain native and/or mutant protein kinase, and in particular tyrosine kinases implicated in a variety of human and animal diseases such as cell proliferative, metabolic, autoimmune, allergic, hematological, inflammatory and degenerative disorders. More particularly, compounds of the invention are potent and selective Syk inhibitors. More in particular, the Applicant evidenced that compounds displaying specific substitutions in oxazole derivatives are potent and selective inhibitors of Syk tyrosine kinase.
The present invention also discloses compounds that are especially stable. More particularly, compounds of the invention are stable over time and/or temperature. More particularly, compounds of the invention display in vivo stability.
The present invention further discloses compounds that are soluble in conventional excipients and/or carriers. More particularly, compounds of the invention are water-soluble.